In a copending patent application Ser. No. 31,271 entitled "Power Tool Apparatus and Method" filed on Apr. 18, 1979, and assigned to the present assignee, there is described a power tool apparatus which employs a rotatably mounted tool such as a saw blade for performing a variety of operations on wood, metal or the like. The apparatus disclosed therein provides a universal-type machine wherein the tool is easily and quickly adjusted for performing operations on a workpiece and wherein means are provided for accurately positioning the tool in relationship to the table top.
The accurate setting of the tool, referred to therein as the vernier adjustment feature, allows for precision cuts as might be needed for miter grooves, molding, shaping, dado cuts and the like.
The prior art described therein deals with a variety of devices employing for the most part only a coarse setting feature. One of the significant objects of that disclosure is to provide a vernier adjustment feature which is operable by the same hand used to set the coarse position of the blade. Towards that end, the application describes a leaf-spring arrangement wherein the leaf spring is disposed along the length of the control lever used to coarsely position the tool. Hub means are disposed at one end of the control lever and are secured to a corresponding end of the leaf spring. The remaining end of the leaf spring is secured to the assembly or subassembly which includes the tool. A knurled knob, concentric with the control lever is disclosed, upon which is disposed the hub to which the one end of the leaf spring is connected. By rotating the knurled knob, the hub is urged axially along the length of the control lever creating an appropriate force which is converted into pivotal movement of the subassembly including the tool such as a saw blade thus providing a vernier adjustment in elevation thereof.
Because of the employment of a leaf-spring to effect the vernier adjustment, there is no solid, structural integrity between the control lever and the subassembly containing the tool. During the cutting or other working operation, this could result in the set elevation not being maintained.
Further, it is conceivable that the leaf-spring in such an arrangement, could snap under certain circumstances.
It is therefore a primary object of this improvement to that basic power tool apparatus to provide means for accommodating the angular changes between the control lever and the assembly containing the tool which obviates the possibility of the set elevation not being maintained.
It is yet another object of this invention to provide an improved elevation setting mechanism which is likewise disposed in close proximity to the control lever so as to be manipulatable by the same hand used by the operator to set the coarse elevation position of the tool.
It is still another object of this invention to provide means for limiting the vernier adjustment of the tool to predetermined limits of elevation.